1. Field of the Invention
The present invention generally relates to an image-sensor emulating device. More particularly, it relates to an image-sensor emulating device capable of emulating image sensor output signals and generating image-sensor timing signals for use in debugging an image processing system or image-sensor under development.
2. Description of the Related Art
FIG. 1 schematically illustrates a circuit block diagram of a scanner 10. In FIG. 1, a light-source driver 101 of the scanner 10 controls a light source (not shown in FIG. 1) to scan an object and obtain an image pattern 102. The image pattern 102 is processed through the mechanism of projection and focus and then received by an image-sensor 103, for example a CCD or CIS device. The image-sensor 103 is controlled by the timing signal (Timing) transmitted from a scanner-engine controller 106. The image pattern 102 processed by the image-sensor 103 is amplified by an amplifier 104 and then inputted to an analog-to-digital (A/D) converter 105, thereby converting the analog image data amplified by the amplifier 104 to digital image data. At the time of A/D conversion, the scanner-engine controller 106 outputs a reference voltage to the A/D converter 105 via a digital-to-analog (D/A) converter 110. The converted digital image data is stored in a memory buffer 109 for further processing via the scanner-engine controller 106. The memory buffer 109, for example, has FIFO structure and consists of SRAM. When the image data are displayed in a host system 108, the scanner-engine controller 106 reads and processes the digital image data from the memory buffer 109. Then the digital image data is sent to the host system 108 for display via an interface controller 107.
In addition to the devices mentioned above, a scanner further comprises an oscillator 111 for providing elementary timing signals, a power-on-reset device 112 for power management, a step-motor driver 113 monitored by the scanner-engine controller 106, and other sensors 114 such as PIP, POP, etc. The scanner can also connect to other peripheral devices, if necessary, via the interface controller 107.
During the process of developing a scanner, if the scanner output images have defects or do not meet the desired level of quality, the problem may originate in the image-sensor 103. For example, the characteristic of the image-sensor 103 could be poor or the image patterns 102 could be distorted by noise before being inputted to the image-sensor 103. If the image-sensor 103 functions without problems, then the problems must occur in the subsequent processing circuits, such as the A/D converter, etc.
At present, function generators can not emulate the output signals of image-sensors or the timing signals controlling the image-sensors. Engineers can not use function generators to emulate xe2x80x9cproperxe2x80x9d output signals of image-sensors and xe2x80x9cproperxe2x80x9d timing signals for triggering the image-sensors to supply to the subsequent processing circuits, thereby testing whether or not the subsequent processing circuits are functioning correctly. Therefore, the debugging process is more complicated and time consuming.
In view of these problems, one object of the present invention is to provide an emulating device for emulating the functions of image-sensors by programmably generating the relevant image-sensor and timing signals. The timing signals also can be generated from timing signals outputted by an outside image-sensor. Therefore, the emulating device can generate predetermined image-sensor signals and timing signals such that the debugging process is simplified and the developing efficiency is also improved. Moreover, the emulating device according to the present invention can also generate a timing signal serving as a reference timing signal for emulating image-sensors. The reference timing signal can be used to compare with the actual timing signals of image-sensors.
In order to achieve the above objects, an image-sensor emulating device is provided for emulating the functions of the image-sensors of an image processing system in a debugging process. The image-sensor emulating device comprises: a controller establishing a link with a host system in which the image processing system displays images by using peripheral interface bus, the controller generating a reference timing signal for sensing images; at least one buffering memory device for storing reference image patterns downloaded from the host system to the controller; and at least one output converter receiving the reference image patterns read from the buffering memory device by the controller and converting the reference image patterns as output signals of the image-sensor emulating device; wherein, the controller reads the reference image patterns in response to the reference timing signal for image sensing generated by the controller itself or a timing signal generated by the image processing system.